New alloying systems for PM-steels: opportunities for the Mn-Si master alloys

Paper in proceedings, 2013

Low alloyed steels containing innovative combinations of alloying elements have been produced though the master alloy route. Fe-Mn-Si master alloy systems were designed to enhance sintering by creating a liquid phase, and were manufactured by gas atomizing in N2. This paper presents an overview of the characteristics of steels modified with Fe-Mn-Si master alloys. Special focus is given to defining the proper conditions for sintering, and to analyzing the level of mechanical properties achievable with standard processing conditions. Although high temperatures (>1300 ºC) are required for reducing highly stable Mn-Si oxides, standard sintering cycles at 1120 and 1250 ºC yielded oxygen contents below 0.1 wt.% and 0.02 wt.% respectively, combined with competitive mechanical properties in the as sintered condition. UTS values around 600 MPa, elongations between 1-3%, hardness values of 200-350 HV10 and impact energies around 10-30 J can be obtain with less than 3 wt.% of alloying elements. Besides, a proper balance of swelling upon liquid phase formation and isothermal shrinkage provides dimensional changes below 0.1 %